JP2002135044A - Circularly polarized wave antenna and circularly polarized wave array antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circularly polarized antenna and a circularly polarized array antenna, which can improve the circularly polarization axial ratio over a wide angular range, can tilt a beam in a state where the circularly polarization axial ratio is satisfactory and can improve the polarized wave identification degree. SOLUTION: A printed die pole antenna 42 formed on a first dielectric substrate 40 and a micro strip patch antenna 32 formed on a second dielectric substrate 30 which is almost orthogonal with the first dielectric substrate and is arranged so that the polarized wave is orthogonal to the polarized wave of the printed dipole antenna 42, are excited by giving the phase difference of 90 degrees. Thus, the E plane directivity characteristic of the micro strip antenna 32 and the H plane directivity characteristic of the printed dipole antenna 42, which mutually have almost equal directivity characteristics, are combined and the circularly polarization axial ratio can be improved over a wide angular range.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a circularly polarized antenna and a circularly polarized array antenna, and more particularly to a circularly polarized antenna and a circularly polarized array antenna used for transmitting and receiving microwaves.

[0002]

2. Description of the Related Art Conventionally, as a microwave antenna, for example, [Omaru: "Printed Antenna", Journal of the Institute of Television Engineers of Japan, Vol. 41, No1, pp98-102 (1
987)], there is a single-point feeding type or two-point feeding type microstrip patch circularly polarized antenna.

FIG. 4 is a plan view of a conventional two-point feeding type circularly polarized microstrip patch antenna. In the figure, a square patch 10 is fed by a microstrip line 12 at two points, a feeding point 14 and a feeding point 16. The feed point 14 has a longer microstrip line 12 so that the phase is delayed by 90 degrees from the feed point 16. As a result, the polarization in the x'-axis direction excited at the feeding point 14 is delayed by 90 degrees with respect to the polarization in the y'-axis direction excited at the feeding point 16, and a right-handed circularly polarized antenna is formed. ing.

[0004] Conventionally, there is a circularly polarized array antenna in which a plurality of circularly polarized antenna elements 20 are arranged as shown in a perspective view of FIG. This circularly polarized antenna element 2
As 0, a two-point feeding type circularly polarized antenna element shown in FIG. 4 or a one-point feeding type circularly polarized antenna element is used. In this case, if all the circularly polarized antenna elements 20 are excited in phase, the maximum circularly polarized wave in the direction perpendicular to the antenna substrate 22 (Z-axis direction) as shown by a broken line 23 in FIG. Of power is radiated.

When the maximum radiation direction is inclined by + θ degrees from the Z-axis direction as shown by a solid line 24 in FIG. 5B, for example, [Haneishi, et al .: "SHF band tilt using circularly polarized pair element" Type planar antenna ", Journal of the Institute of Television Engineers of Japan, Vo
l. 41, No. 7, pp. 642-647 (1987)]
As described in the above section, the feeding line length is changed so that the radiation phases from the respective antenna elements 20 are in phase in the + θ degree direction.

[0006]

The circularly polarized antenna shown in FIG. 4 is excited from the feeding points 14 and 16 and generates mutually independent orthogonal electric field distributions in the x 'direction and the y' direction, respectively. At this time, the electric field in the x ′ direction is 90
A right-handed circularly polarized wave can be emitted or received by delaying by 90 degrees, and a left-handed circularly polarized wave can be emitted or received by delaying the y 'direction by 90 degrees.

At this time, the directional characteristics of the x'z 'plane include an E-plane radiation pattern (a plane including the electric field vector and the maximum radiation direction) when excited from the feeding point 14 and an H-plane when excited from the feeding point 16. A radiation pattern (a plane including the magnetic field vector and the maximum radiation direction) is a combined pattern. The directional characteristics of the y′z ′ plane include an H-plane radiation pattern (a plane including a magnetic field vector and a maximum radiation direction) when excited from the feed point 14 and an E-plane radiation pattern (an electric field vector) when excited from the feed point 16. And a plane including the maximum radiation direction).

FIG. 6 shows an example of actually measured values of the radiation directivity characteristics of the E-plane and the H-plane of the microstrip antenna. This figure is described in [Antenna Engineering Handbook, p. 109, Ohmsha, 1980]. As shown in FIG. 6, a 0 degree direction (corresponding to the z ′ axis direction in FIG. 4)
The radiation power of the E-plane and the H-plane is equal up to the direction of about 30 degrees from, but the radiation power of the E-plane and the H-plane differs when the angle exceeds 30 degrees. As a result, the circular polarization axis ratio in the 0-degree direction is improved, but when the angle exceeds 30 degrees, the radiated powers of the E plane and the H plane are different, so that the circular polarization axis ratio is rapidly deteriorated.

For this reason, for example, when receiving a circularly polarized wave arriving from an angle θ direction of 40 degrees or 50 degrees, a sufficient circular polarization axis ratio cannot be obtained, and the polarization discrimination degree deteriorates. May not be able to receive or transmit the desired radio wave.

In addition, a circularly polarized wave array antenna having a large number of circularly polarized antenna elements is used as a planar antenna for receiving satellite broadcasting, and is mounted in close contact with a wall of a house perpendicular to the ground, and is tilted and beam-tilted. For example, at the latitude of Tokyo, it is necessary to tilt the beam from the horizontal direction to the sky direction by 38 degrees. Also in this case, the angle θ is 30
Degree, the circular polarization axis ratio of each circular polarization antenna element is degraded, so the circular polarization axis ratio is degraded even in the case of arraying. This circular polarization array antenna has sufficient polarization discrimination. There was a problem that can not be.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and can improve a circular polarization axis ratio over a wide angle, and can perform beam tilting with a good circular polarization axis ratio to enable polarization identification. It is an object of the present invention to provide a circularly polarized antenna and a circularly polarized array antenna having improved degrees.

[0012]

According to a first aspect of the present invention, there is provided a printed dipole antenna formed on a first dielectric substrate, and a second dielectric substantially orthogonal to the first dielectric substrate. A microstrip patch antenna formed on a substrate and arranged so that the polarization is orthogonal to the polarization of the printed dipole antenna, wherein the printed dipole antenna and the microstrip patch antenna are arranged at about 90 degrees. By providing the phase difference and exciting, it is possible to improve the circular polarization axis ratio over a wide angle by combining the E-plane directivity of the microstrip antenna having substantially the same directivity as the H-plane directivity of the printed dipole antenna.

According to a second aspect of the present invention, there is provided a printed dipole antenna formed on a first dielectric substrate, and a printed dipole antenna formed on a second dielectric substrate substantially orthogonal to the first dielectric substrate. A microstrip patch antenna arranged so that the polarization is orthogonal to the polarization of the printed dipole antenna;
A plurality of circularly polarized antenna elements that are excited with a phase difference of degrees are arranged on the same plane, and each circle is so arranged that the radiation phase from each circularly polarized antenna element in a certain direction in space is in phase. By exciting the polarized antenna elements with a predetermined phase difference, the circularly polarized axis ratio of each circularly polarized antenna element can be improved, and even when the beam is tilted obliquely from a direction perpendicular to the antenna surface. A large circular polarization axis ratio can be obtained, and the polarization discrimination can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The circularly polarized antenna of the present invention is generated by combining an E-plane radiation pattern of a microstrip antenna and an H-plane radiation pattern of a printed dipole antenna.

As a microstrip antenna, a rectangular patch antenna or a circular patch antenna is excited with linear polarization by feeding at one point. On the other hand, as a printed dipole antenna, for example, [B. Edward an
d D. Rees, "A Broadband Pri
nted Dipole with Integrat
ed Balun ", Microwave Journal
al, pp. 339-344, May 1987]. The H-plane directivity of the printed dipole antenna has a wide directivity on the H-plane as shown in FIG. 7 (excerpted from the above-mentioned document pp. 344), and the directional characteristic of the E-plane of the microstrip antenna shown in FIG. The directional characteristics are almost the same across the board. In other words, by combining the E-plane directivity of the microstrip antenna and the H-plane directivity of the printed dipole antenna to produce a circularly polarized wave, it is possible to obtain a circularly polarized wave having an excellent axial ratio over a wide angle.

FIG. 1 is a perspective view of a circularly polarized antenna according to a first embodiment of the present invention. In the figure, a microstrip antenna 32 is formed on a dielectric substrate 30. The microstrip antenna 32 is excited by a polarized wave in the x-axis direction from a feed point 34. The back surface of the dielectric substrate 30 with respect to the surface on which the microstrip antenna 32 is formed is a grounded conductor surface 36.

On the other hand, a printed dipole antenna 4 is provided on a dielectric substrate 40 substantially orthogonal to the dielectric substrate 30.
2 are formed. Print dipole antenna 42
Is excited by the feed line 44 with the polarization in the y-axis direction. The feeder line 44 is provided on the back surface side of the dielectric substrate 40 with respect to the surface on which the printed dipole antenna is formed. The surface of the dielectric substrate 40 on which the printed dipole antenna is formed is divided into two parts by the dielectric substrate 30, one of which is provided with the printed dipole antenna 42 and the other is provided with the grounded conductor surface 4.
6.

The microstrip antenna 32 and the printed dipole antenna 42 are arranged close to each other with the same position in the y-axis direction, and the phases of the high-frequency signals fed from the feed point 34 and the feed line 44 are made different by 90 degrees. By exciting the antenna 32 and the printed dipole antenna 42 with a phase difference of 90 degrees,
The E-plane radiation pattern of the microstrip antenna 32 and the H-plane radiation pattern of the printed dipole antenna 42 are combined, and transmission or reception can be performed with right-handed or left-handed circularly polarized waves.

In this circularly polarized antenna, since the E-plane directivity of the microstrip antenna and the H-plane directivity of the printed dipole antenna are almost equal over a wide angle, a good axial ratio is obtained over a wide angle. Can be obtained.

FIGS. 2A, 2B and 2C are plan and front views of a first embodiment of a circularly polarized array antenna according to the present invention.
FIG. In this embodiment, a circularly polarized antenna element is constituted by a microstrip antenna and a printed dipole antenna, and a plurality of circularly polarized antenna elements are arranged in the x and y axis directions.

2 (A), 2 (B) and 2 (C), a plurality of microstrip antennas 5
2 are formed. Each microstrip antenna 5
Numeral 2 is excited from the feeding point 54 by polarized light in the x-axis direction. The back surface of the dielectric substrate 50 with respect to the surface on which the microstrip antenna 52 is formed is a grounded conductor surface. Note that y
The distance between the feed points 54 of the microstrip antennas 52 adjacent in the axial direction is set to a predetermined distance L1, and the feed point 5 of the microstrip antenna 52 adjacent in the x-axis direction is set.
The interval of 4 is a predetermined distance L2.

On the other hand, on the dielectric substrate 50, a plurality of dielectric substrates 60 are erected substantially vertically at a predetermined distance L2 in the x-axis direction. On each dielectric substrate 60, a plurality of printed dipole antennas 62 are disposed at a predetermined distance L in the y-axis direction.
They are formed separated by one. Each printed dipole antenna 62 is excited by a feed line 64 with a polarized wave in the y-axis direction. The power supply line 64 is provided on the back surface side of the surface of the dielectric substrate 60 on which the printed dipole antenna is formed. The surface of the dielectric substrate 60 on which the printed dipole antenna is formed is divided into two by the respective dielectric substrates 50, one of which is formed with the printed dipole antenna 62 and the other is a grounded conductor surface 66.

The wavelength of the transmitted / received microwave is λa
In general, the predetermined distances L1 and L2 are smaller than λa. If it is desired to have a directional characteristic that radiates with the largest power in the front direction (z-axis direction) of the antenna, the predetermined distances L1, L2
Both are about 0.8λa, but when it is desired to incline the beam from the front in the yz plane, the predetermined distance L1 is about 0.5λa, depending on the angle of inclination. Even if the predetermined distances L1 and L2 are other than the above values, the operation as an antenna is performed, but the characteristics are deteriorated.

A plurality of microstrip antennas 52 arranged in the y-axis direction and a plurality of printed dipole antennas 62 arranged in the y-axis direction on a dielectric substrate 60 opposed to the microstrip antennas at an angle of approximately 90 degrees constitute a sub-array 70. The microstrip antenna 52 and the printed dipole antenna 62 adjacent to each other in the sub-array 70 are arranged close to each other while being shifted by a predetermined distance L3 (L3 = L1 / 2) in the y-axis direction, and a circularly polarized antenna element is disposed. Make up. Further, by making the phase of the high-frequency signal fed from the feed point 54 and the feed line 64 different by 90 degrees, the E-plane radiation pattern of the microstrip antenna 52 and the H-plane radiation pattern of the printed dipole antenna 62 are combined, and The wave antenna element can transmit or receive right-handed or left-handed circularly polarized waves.

The sub-array 70 adjacent in the x-axis direction
By sequentially shifting the relative phase of the circularly polarized antenna element by a predetermined angle between them, it becomes possible to tilt the beam in the x-axis direction. Further, by equalizing the phase between the plurality of sub-arrays 70 and sequentially shifting the relative phase between the circularly polarized antenna elements adjacent in the y-axis direction by a predetermined angle,
Beam tilt can be performed in the y-axis direction. Of course, it is also possible to form a beam in an arbitrary direction by individually changing the phase of the circularly polarized antenna elements constituting the array.

In this embodiment, since the microstrip antennas 52 and the printed dipole antennas 62 are alternately arranged and are not too close to each other, good directional characteristics can be obtained without disturbing the mutual radiation pattern.

FIG. 3 is a plan view of a circularly polarized array antenna according to a second embodiment of the present invention. In this embodiment, a circular patch antenna is used as a microstrip antenna, a circularly polarized antenna element is formed by a printed dipole antenna, and a plurality of circularly polarized antenna elements are arranged in the x and y axis directions.

In the figure, a plurality of pairs of microstrip antennas 82A and 82B are formed on a dielectric substrate 80. Each pair of microstrip antennas 82A, 82B
Is excited from the feeding point 84 through the microstrip line 86 with the polarization in the x-axis direction. The back surface of the dielectric substrate 80 with respect to the microstrip antenna forming surface is a grounded conductor surface. The distance between the microstrip antennas 82A and 82B adjacent in the y-axis direction is a predetermined distance L4, and the distance between the microstrip antennas 82A and 82B adjacent in the x-axis direction is a predetermined distance L5.

On the other hand, a plurality of dielectric substrates 90 are erected substantially vertically on the dielectric substrate 80 with a predetermined distance L5 therebetween. On each dielectric substrate 90, a plurality of printed dipole antennas 92A and 92B are formed separated by a predetermined distance L1. Each printed dipole antenna 9
2A and 92B are excited by the feed lines 94A and 94B with the polarization in the y-axis direction. The power supply line 94 is connected to the dielectric substrate 90
Of the printed dipole antenna. Also, the surface on which the printed dipole antenna of the dielectric substrate 90 is formed is divided into two by the respective dielectric substrates 80, and the printed dipole antennas 92A and 92B
Is formed, and the other is a grounded conductor surface.

A plurality of microstrip antennas 82A and 82B arranged in the y-axis direction and a plurality of printed dipole antennas 92A and 92B arranged in the y-axis direction on a dielectric substrate 90 opposed to the microstrip antennas at an angle of approximately 90 degrees are provided. The sub-array 100 is formed, and the microstrip antennas 82A and 82B and the printed dipole antennas 92A and 92B adjacent to each other in the sub-array 100 are arranged close to each other so that their positions in the y-axis direction are matched to form a circularly polarized antenna element. are doing. The phase of the high-frequency signal supplied from the power supply point 84 and the power supply lines 94A and 94B is set to 90.
By making the degrees different, each circularly polarized antenna element can transmit or receive right-handed or left-handed circularly polarized waves.

Also in this embodiment, the beam can be tilted in the x-axis direction by sequentially shifting the relative phase of the circularly polarized antenna element by a predetermined angle between the sub-arrays 100 adjacent in the x-axis direction. In addition, a plurality of sub-arrays 1
The beam tilt in the y-axis direction can be achieved by equalizing the phases between 00 and 00 and sequentially shifting the relative phase between the circularly polarized antenna elements adjacent in the y-axis direction by a predetermined angle. Of course, it is also possible to form a beam in an arbitrary direction by individually changing the phase of the circularly polarized antenna elements constituting the array.

Further, since the microstrip antennas 82A and 82B and the microstrip line 86 are formed on the dielectric substrate 80 at the same time, it is easy to form a fixed-length feed line (microstrip line 86), and the beam is inclined at an angle. It is suitable when is determined. On the other hand, in the embodiment of FIG. 2, the power supply line may be complicated because power is supplied to each microstrip antenna 52 from the back surface of the dielectric substrate 50. By changing the feeding phase of the antenna 52, the angle of tilting the beam can be changed freely.

The dielectric substrates 40, 60, 90 correspond to the first dielectric substrate described in the claims, and the dielectric substrates 30,
50 and 80 correspond to the second dielectric substrate.

[0034]

As described above, the first aspect of the present invention provides
A printed dipole antenna formed on a first dielectric substrate, and a polarization orthogonal to the polarization of the printed dipole antenna formed on a second dielectric substrate substantially orthogonal to the first dielectric substrate. And a microstrip patch antenna arranged in such a manner that a 90 ° phase difference is provided between the microstrip patch antenna and the microstrip patch antenna. Can be combined to improve the circular polarization axis ratio over a wide angle.

According to a second aspect of the present invention, there is provided a printed dipole antenna formed on a first dielectric substrate and a printed dipole antenna formed on a second dielectric substrate substantially orthogonal to the first dielectric substrate. A micro-strip patch antenna arranged so that the polarization is orthogonal to the polarization of the printed dipole antenna and a plurality of circularly-polarized antenna elements which are excited with a phase difference of 90 degrees are arranged on the same plane. By exciting each circularly polarized antenna element with a predetermined phase difference so that the radiation phase from each circularly polarized antenna element in a certain direction of space becomes the same phase, the circularly polarized antenna elements are circularly polarized. The wave axis ratio can be improved, and a good circular polarization axis ratio can be obtained even when the beam is tilted obliquely from a direction perpendicular to the antenna surface, and the polarization discrimination is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a circularly polarized antenna according to a first embodiment of the present invention.

FIG. 2 is a plan view, a front view, and a rear view of the first embodiment of the circularly polarized array antenna of the present invention.

FIG. 3 is a plan view of a circularly polarized array antenna according to a second embodiment of the present invention.

FIG. 4 is a plan view of a conventional two-point feeding type circularly polarized microstrip patch antenna.

FIG. 5 is a perspective view and a directional pattern of a conventional array antenna.

FIG. 6 is a special radiation pattern on the E and H planes of the microstrip antenna.

FIG. 7 is a special radiation pattern on the E-plane and the H-plane of the printed dipole antenna.

[Explanation of symbols]

30, 40, 50, 60, 80, 90 Dielectric substrate 32, 52, 82A, 82B Microstrip antenna 34, 54, 84 Feed point 36, 46, 66 Conductor surface 42, 62, 92A, 92B Printed dipole antenna 44, 64,94A, 94B power supply line 70,100 sub-array

Claims (2)

[Claims] A printed dipole antenna formed on a first dielectric substrate; and a printed dipole antenna formed on a second dielectric substrate substantially orthogonal to the first dielectric substrate. A microstrip patch antenna arranged so that the polarization is orthogonal to the antenna, wherein the printed dipole antenna and the microstrip patch antenna are excited with a phase difference of 90 degrees. Wave antenna. 2. A printed dipole antenna formed on a first dielectric substrate and a polarized wave of the printed dipole antenna formed on a second dielectric substrate substantially orthogonal to the first dielectric substrate. A plurality of circularly polarized antenna elements comprising a microstrip patch antenna whose polarizations are orthogonal to each other, wherein the printed dipole antenna and the microstrip patch antenna are excited with a phase difference of 90 degrees. It is arranged on the same plane, and it is characterized by exciting each circularly polarized antenna element with a predetermined phase difference so that the radiation phase from each circularly polarized antenna element in a certain direction of space becomes the same phase. Circularly polarized array antenna.